Health: Dear doctor

Q I take ecstasy once or twice a week when clubbing or out with friends. Is it going to damage me mentally in the long-term?

A Ecstasy (MDMA) is a powerful, potentially dangerous drug which can damage the nerves in the brain that produce serotonin, one of the chemical messengers within the nervous system. Animals who are given MDMA end up with low serotonin levels, which don't recover for years. Studies have shown similar effects in humans. We don't really know what long-term effects this might produce. Depression is associated with low serotonin levels and anti-depressants such as Prozac work by increasing the levels. But whether twice weekly ecstasy will make you depressed or mentally unwell in the long-term is not certain. The devil you know may be safer than fake ecstasy tablets which are widely sold.

Q I suffered terrible postnatal depression after my first baby was born and although I would like another child I am concerned about future pregnancies. Is it likely to happen again, and is there anything I can do?

A Having been through it once, you are at increased risk of it happening again but are also well placed to recognise the signs and seek help promptly. You will know that postnatal depression is worse than the baby blues that affects 80% of all new mums. It is still common, affecting over 10% of all women postnatally. You feel despondent, uninterested in the baby and your own wellbeing, unable to cope, guilty, panicky, unable to eat or sleep properly, edgy and preoccupied by obsessional thoughts that race around your head. Health professionals use questionnaires such as the Edinburgh Postnatal Depression Scale to assess whether you're depressed. Help from friends, family, employers and health professionals including midwife, health visitor and GP can reduce your risk of becoming depressed this time. Having postnatal depression doesn't make you a bad or inadequate mother. On the contrary, many women battle against huge internal angst and still manage to care for their baby wonderfully.

TV or not TV?

Q My 14-year-old daughter has only two leisure activities; shopping and watching television. During term time, she doesn't have time to shop but watches TV every spare moment. She says there's no harm in it and that she does plenty of running about at school. Is she right?

A You may want to tell her about a new report in Science magazine, showing that young women who watch television for more than two hours a day become aggressive adults. Adolescents of both sexes who watch more than an hour a day also turn into aggressive adults with boys behaving worse than girls. This is very bad news for all of us as I don't know any adolescent who watches under an hour a day (EastEnders followed by Holby City mops up an hour-and-a-half, which, my daughter assures me, is not a lot at all). You are probably thinking that it is not television watching that produces aggressive, horrible adults; there are other factors such as poverty, neglect and mental illness. But much as I hate to rattle middle-class complacency, the association between television watching and aggression remains even once you correct for these other variables.

Lazy bowels

Q I get very constipated and bloated unless I take Senna. My GP has said that my bowel will get lazy and I must try to stop the laxatives. But when the pressure builds up I feel very uncomfortable and lethargic. What can I do?

A As a nation, we're less constipated than we imagine. Many think they need laxatives and more than £46m of NHS laxative prescribing is flushed down the toilet every year. Increasing your fibre and fluid intake and doing more exercise is enough to help. A cheap laxative that adds bulk to the stool, such as Fybogel, is a good start. If that is not enough, Senna or other stimulant laxatives, can be added. Osmotic laxatives that draw fluid into the stool, such as lactulose, is less effective than a Fybogel/ Senna combo.

· These answers are intended to be as accurate and full as possible, but should never be used as a substitute for visiting a doctor and seeking medical help. If you have a question for Dr Robinson, email drann@dircon.co.uk or write to her c/o The Health Editor, The Guardian, 119 Farringdon Road, London EC1R 3ER. She regrets that she cannot enter into personal correspondence.